The Small Animal Cancer Imaging Research Facility (SACIRF) provides cancer investigators with the latest technology and techniques for experimental in vivo imaging of small animals. The facility includes state-ofthe- art instrumentation, including the modalities of magnetic resonance (MR, Bruker4.7 T, 40 cm Biospec), x-ray computed tomography (micro-CT from Enhanced Vision Systems and volume CT being developed in collaboration with General Electric), projection radiography (Faxitron), and nuclear imaging (M.Cam gamma camera from Siemens and micro-PET from Concorde Microsystems). Optical imaging will be added during the first year of the award (instrumentation to be developed in collaboration with Biomedical Engineering at The University of Texas-Austin). This instrumentation represents a >$3M investment by MDACC. The SACIRF has allocated space for the instruments in the animal support facilities to facilitate the inclusion of the imaging studies in ongoing cancer research, and dedicated office and developmental laboratory space to support the facility operation. The faculty and staff are well-qualified in each of the modality areas, including current image acquisition and image analysis techniques. Specialty areas include quantitative tissue characterization (MR), imaging of microvascular physiology (MR, nuclear, CT and optical), diffusion imaging for estimating cellular density (MR), metabolic imaging (nuclear, positron emission tomography [PET], optical and MR spectroscopy), and vascular imaging (MR, CT, and x-ray). The services of the facility include imaging protocol design, custom positioning systems, custom data acquisition hardware and software, image analysis, data archiving, provision of hardcopy and digital data delivery, and database maintenance. The Veterinary Core includes a dedicated support team that provides highly efficient imaging studies and a very low mortality rate of animals during the imaging procedures. Services provided from the Veterinary Core include development of veterinary support protocols specific to each experimental design, and consultation on the inclusion of imaging procedures into existing protocols to obtain Institutional Animal Care and Use Committee approval. To date, 75 investigators representing 13 programs have used facility instrumentation. 42% of the users are peer-review-funded investigators. Utilization continues to increase as the facility and its capabilities become better known to the local cancer research community. The capabilities of the facility continue to grow to meet experimental demands. Publications are evolving at a rapid pace, and although only a few are published, the acceptance rate has been nearly 100%. Funding for the SACIRF is currently CCSG (43%), user fees (36%), and MDACC (21%).